Haloacetic Acid 5 (HAA5) MCL Violation at Dartmouth Water Division
Important Notice

Our water system recently violated a drinking water standard. Although this incident was not an emergency, as our customers, you have a right to know what happened and what we are doing to correct this situation.

We routinely monitor for the presence of drinking water contaminants. Testing results from August 2021 show that our system exceeded the standard or maximum contaminant level (MCL), for HAA5. The standard for HAA5 is 60 parts per billion (ppb). It is determined by averaging all samples collected at each sampling location for the past 12 months. The level of HAA5 averaged at our system Reed Road location for August was 72 parts per billion (ppb). Although the sample results improved for this site it was not enough to reduce the 12 month average.

What should I do?

  • There is nothing you need to do. You do not need to boil your water or take other corrective actions. If a situation arises where the water is no longer safe to drink, you will be notified within 24 hours.
  • If you have a severely compromised immune system, have an infant, are pregnant, or are elderly, you may be at increased risk and should seek advice from your health care providers about drinking this water.

What does this mean?

This is not an emergency. If it had been an emergency, you would have been notified within 24 hours. HAA5 are five haloacetic acid compounds, which form when disinfectants react with natural organic matter in the water.

People who drink water containing haloacetic acids in excess of the MCL over many years may have an increased risk of getting cancer. Please see  for a fact sheet on HAA5s.

What is being done?

Daily flushing for this location is scheduled for this location. The Town has been working on a comprehensive plan to address HAA5 concerns for several years.  Ongoing distribution improvements have been underway throughout the town. Currently water mixing systems are being used in four water storage tanks. The Town converted from chlorine to chloramines as a means of disinfecting our water in March 2021. We anticipate that the Town’s comprehensive plan will resolve ongoing water quality concerns over the next 12 months. For more information, please contact Steven Sullivan at 508-999-0742,

Please share this information with all the other people who drink this water, especially those who may not have received this notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can do this by posting this notice in a public place or distributing copies by hand or mail.

This notice is being sent to you by Dartmouth.    PWS ID#: 4072000   Date distributed 9/13/2021